The invention relates to an emulsion of a viscous hydrocarbon in an aqueous buffer solution for use as a combustible fuel.
Low gravity viscous hydrocarbons are found in large supply in Canada, Russia, the United States, China and Venezuela, and are normally liquids with viscosities ranging from 10,000 cp to more than 500,000 cp at ambient temperatures. These hydrocarbons are typically produced by numerous methods including steam injection, mechanical pumping, mining techniques and combinations of these methods.
Once produced, such hydrocarbons are useful as combustible fuel once they are desalted and dehydrated and have been treated to remove other undesirable constituents. As a liquid fuel, however, these hydrocarbons are too viscous for practical use. Thus, such viscous hydrocarbons are formed into hydrocarbon in water emulsions which have improved viscosity and, accordingly, improved flow characteristics. When formed with a high ratio of hydrocarbon material to water, these emulsions are an excellent combustible fuel. However, the emulsion is not stable and rapidly breaks if not stabilized with surfactants or emulsifiers. Unfortunately, commercial emulsifiers are expensive and the cost of the emulsion is therefore increased. This added cost obviously adversely impacts the viability of using viscous hydrocarbons to form combustible fuel emulsions.
Viscous hydrocarbons are known to naturally contain materials which are potential surfactants. It would of course be desirable to activate such materials so as to provide natural surfactants to stabilize the emulsion without the additional expense of commercial emulsifiers, thereby providing a more practical alternative for the use of viscous hydrocarbons in forming combustible fuel emulsions. The materials naturally contained in viscous hydrocarbons which are potential surfactants include numerous carboxylic acids, esters and phenols which, in basic pH environment, can be activated as natural surfactants. Sodium hydroxide has been used as an additive to provide the proper pH. However, sodium hydroxide is unable to keep the pH of the aqueous phase constant so that the proper pH, the activated surfactant and the emulsion itself are all short lived.
It is desirable, accordingly, to provide an emulsion stabilized with natural surfactants which does not require the addition of commercial surfactants and which emulsion resists aging and is useful as a combustible liquid fuel.
Accordingly, it is the principal object of the present invention to provide a combustible emulsion of a viscous hydrocarbon in water which emulsion utilizes the natural surfactants of the hydrocarbon to provide stability.
It is a further object of the invention to provide a method for forming such a combustible emulsion.
It is a still further object of the invention to provide such an emulsion and method whereby the emulsion formed is a bimodal emulsion having improved viscosity characteristics.
Other objects and advantages will appear hereinbelow.